Usually it is a good idea to loosen the roots a little bit so they are directed outward from the original soil ball and so the sides of the rootball are not totally smooth. Then nestle the plant into the loose soil in the hole so there is good soil to root contact. If they are very rootbound with tightly wound circles or a hard mass of roots it is critical to do that. If the roots are not terribly crowded and your soil is well prepared and loose, then it is less important.